Tunable elements of an RF circuit can allow tuning a circuit based on specific frequencies of operation of the circuit which can change, for example, in dependence of a frequency band of operation of the circuit. Such tuning can allow, for example, tuning of RF frontend blocks used in RF communication systems, such as handheld and portable devices, for optimization of their performance over a wide range of frequencies. Tunable circuits used in such RF frontend blocks may include, for example, one or more of power amplifiers (PA's), low noise amplifiers (LNA's), antenna tuners, filters, couplers, mixers and other, as descried, for example, in the above referenced Tunable Circuits Applications, the disclosures of which are incorporated herein by reference in their entirety. Tunable elements of such tunable circuits may include circuits and/or components whose characteristics can be controlled, via either analog or digital control signals. Exemplary tunable elements include digitally tunable capacitors and/or inductors (DTCs, DTLs) as described in the above referenced U.S. Pat. No. 9,024,700 B2 and U.S. Pat. No. 9,197,194 B2, where capacitance and inductance may be controlled via digital control signals (e.g. words). When used in a tunable circuit, DTCs and/or DTLs can change, for example, a frequency response of the circuit based on the provided digital control signals.
In cases where the tunable circuit is monolithically integrated as an integrated circuit (IC), a system integrator using such IC may need to include auxiliary support blocks (firmware/software/hardware) that generate and feed to the IC, frequency based control signals for each tunable element of the IC in order to tune the tunable circuit. In other words, tuning of the tunable circuit may require, for example, detecting and/or establishing a change in an effective operating frequency of the tunable circuit, measuring and/or establishing the effective operating frequency, based on the measured/established frequency, generating control signals for each of the tunable elements of the tunable circuit, and send the generated control signals to the tunable circuit. Such auxiliary support blocks may add to system complexity, integration cost, and physical size, which together, may render usage of such tunable IC less desirable to some system integrators.